Among techniques related to this type of fuel cell stack, there is one having a configuration disclosed in Japanese Patent Application Publication No. 2005-158670 which is titled “FUEL CELL SYSTEM”.
The fuel cell system disclosed in Japanese Patent Application Publication No. 2005-158670 includes: fuel cells each having an electrolyte, a first catalyst layer joined to one side of the electrolyte, a second catalyst layer joined to the other side of the electrolyte, a first electrode joined to the side of the first catalyst layer opposite to the electrolyte, a second electrode joined to the side of the second catalyst layer opposite to the electrolyte, and a separator joined to the first electrode; a first reaction gas supply unit configured to supply a first reaction gas to the first electrode; a second reaction gas supply unit configured to supply a second reaction gas to the second electrode; and a control unit configured to control operations of the fuel cell system. The first electrode has a two-layer-passage structure including an electrolyte-side gas supply passage disposed on the electrolyte side in a stacking direction of the fuel cells and a separator-side gas supply passage disposed on the separator side in the stacking direction.
In the fuel cell system of the related art described above, there is shown a configuration in which a coolant passage portion is formed between the stacked fuel cells and the coolant passage portion includes an elastic body (pre-load plate) for applying a compressive elastic load to the first electrode.
The pre-load plate described above is intended to distribute a load locally generated due to form errors in constituent parts of the fuel cells such as the MEAs, the hydrogen electrodes, the oxygen electrodes, and the coolant passage portions, so that the load can be evenly applied to the constituent parts.